• 대한기계학회논문집B
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• 제29권6호
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• pp.763-771
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• 2005

This paper is an experimental study on the performance according to a capillary tube diameter and length in a domestic small multi refrigerator[kimchi refrigerator]. Pressure drop in a capillary tube is predicted by theoretical analysis and experimental method as the reduction of capillary tube diameter from 0.74 to 0.6 mm. The differences between experimental results and analytical results are mainly caused by friction factor in a capillary tube. Because there are no adequate equations used to calculate pressure drop of capillary tube diameter under 1.0mm. The empirical equations necessary for interpretation of capillary tube were derived from capillary tube test results data using curve fitting method. This study shows that the optimized designs of system, which is capillary tube length and refrigerant charge amount, are 2000mm, 83g at the capillary tube diameter 0.6mm and 3000mm, 73g at the capillary tube diameter 0.74mm. And capillary design tools and system matching techniques necessary for development of the kimchi refrigerator were also developed through this study.

• 한국연초학회지
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• 제24권1호
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• pp.27-31
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• 2002

Three kinds of inoculation methods, capillary, root cutting and dipping were compared for an efficient way to screening the resistant tobacco variety against bacterial wilt, Ralstonia solanacearum. The pricking a capillary tube contained the pathogenic bacterial suspension(10$^{7}$ cfu/$m\ell$) to an axillary bud of each tobacco plant showed different resistance well between varieties. The less period was required in inoculating work and in disease development for the inoculation method used with capillary tube than for two other inoculation methods tested also.

• Journal of Mechanical Science and Technology
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• 제16권12호
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• pp.1719-1724
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• 2002

A previously designed capillary viscometer with measuring differential pressure was modified to measure the viscosity of non-Newtonian fluids including unadulterated blood continuously over numerous shear rates in a single measurement. Because of unavoidable experimental noise and a limited number of data, the previous capillary viscometer experienced an inaccuracy and could not directly determine a viscosity without an iterative calculation. However, in the present measurement there are numerous data available near the point of interest so that the numeric value of the derivative, d(In Q)/d(In Q$\sub$w/), is no longer sensitive to the method of differentiation. In addition, relatively low and wide shear rate viscosity measurements were possible because of the present precision pressure-scanning method with respect to time. For aqueous polymer solutions, excellent agreement was found between the results from the pressure-scanning capillary viscometer and those from a commercially available rotating viscometer. In addition, the pressure-scanning capillary viscometer measured the viscosity of unadulterated whole blood without adding any anticoagulants.

• 분석과학
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• 제19권4호
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• pp.275-279
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• 2006

A capillary electrophoresis method for the separation of carvedilol and its metabolites enantiomers using cyclodextrins as the chiral selectors was developed. The effect of several types of cyclodextrins, concentration and capillary temperature for enantiomer resolution were investigated. Best results were obtained by 15 mM carboxymethyl-${\beta}$-cyclodextrin in the run buffer. Also the effect of capillary temperature on efficiency was assessed. The optimized method was applied for separation of chiral carvedilol and its three metabolites.

• Journal of Mechanical Science and Technology
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• 제16권2호
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• pp.255-261
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• 2002

A newly designed mass-detecting capillary viscometer uses a novel concept to continuously measure non-Newtonian fluids viscosity over a range of shear rates. A single measurement of liquid-mass variation with time replaces the now rate and pressure drop measurements that are usually required by capillary tube viscometers. Using a load cell and a capillary, we measured change in the mass flow rate through a capillary tube with respect to the time, m(t), from which viscosity and shear rate were mathematically calculated. For aqueous polymer solutions, excellent agreement was found between the results from the mass-detecting capillary viscometer and those from a commercially available rotating viscometer. This new method overcomes the drawbacks of conventional capillary viscometers meassuring non-Newtonian fluid viscosity. First, the mass-detecting capillary viscometer can accurately and consistently measure non -Newtonian viscosity over a wide range of shear rate extending as low as 1 s$\^$-1/. Second, this design provides simplicity (i. e., ease of operation, no moving parts), and low cost.

• 한국전산유체공학회지
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• 제12권4호
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• pp.14-19
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• 2007

We present a direct numerical simulation technique and some preliminary results of the capillary spreading of a droplet containing particles on the solid substrate. We used the level-set method with the continuous surface stress for description of droplet spreading with interfacial tension and employed the discontinuous Galerkin method for the stabilization of the interface advection equation. The distributed Lagrangian-multipliers method has been combined for the implicit treatment of rigid particles. We investigated the droplet spreading by the capillary force and discussed effects of the presence of particles on the spreading behavior. It has been observed that a particulate drop spreads less than the pure liquid drop. The amount of spread of a particulate drop has been found smaller than that of the liquid with effectively the same viscosity as the particulate drop.

• Tribology and Lubricants
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• 제38권5호
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• pp.185-190
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• 2022

Among the operating limits of a heat pipe, the capillary limit is significantly affected by the characteristics of the wick, which is determined by the capillary performance. The major parameters for determining capillary performance are the maximum capillary pressure and the spreading characteristics that can be expected through the wick. A well-designed wick structure improves capillary performance and helps improve the stability of the heat pipe by enhancing the capillary limit. The capillary performance can be improved by forming a porous microstructure on the surface of the wick structure through surface modification techniques. In this study, a microstructure is formed on the surface of the wick by using a surface modification method (i.e., an electrochemical etching process). In the experiment, specimens are prepared using stainless-steel screen mesh wicks with various fabrication conditions. In addition, the spreading and capillary rise performances are observed with low-surface-tension fluid to quantify the capillary performance. In the experiments, the capillary performance, such as spreading characteristics, maximum capillary pressure, and capillary rise rate, improves in the specimens with microstructures formed through surface modification compared with the specimens without microstructures on the surface. The improved capillary performance can have a positive effect on the capillary limit of the heat pipe. It is believed that the surface microstructures can enhance the operational stability of heat pipes.

• 분석과학
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• 제12권4호
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• pp.341-345
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• 1999

The separation and determination of inorganic cations by a capillary zone electrophoresis was studied. Cations were separated by the capillary column and detected by indirect UV method. The running buffer of 0.03 M creatinine and 0.02 M-hydroxy isobutylic acid solution (pH 4.8) was used to improve the mobility of ions in the column. A potential of 18 kV was applied at anode. A complete separation of cations ranged within 15 min and detection limits were between 0.1 and 1.0 ppm. The applicability of the method for real samples was demonstrated.

• 약학회지
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• 제41권5호
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• pp.539-546
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• 1997

Capillary electrophoresis (CE) is perceived as an attractive tool for the analysis of pharmaceuticals and biological materials because of their high separation efficiency, easy separation and low running cost. New concept of micellar electrokinetic capillary chromatography (MECC) expanded the application of CE to the separation of neutral molecules. Validation of CE as an analytical technique for quality control of pharmaceuticals should be confirmed by quantitative analysis and the peak confirmation. In this study, the quantitative analyses of various types of neutral, acidic and basic components (acetaminophen, caffeine, ascorbic acid, riboflavin, thiamine, chlorpheniramine, phenylpropanolamine, dl-methylephedrine and dextromethorphan) in complex cold medicines have been accomplished using CE. Combined methods of MECC using SDS and capillary zone electrophoresis lowering the pH of running buffer were adopted to determine the ingredients in capsule type or liquid formula complex medicines without particular sample pretreatment. The results indicate that CE is a promising technique for quality control analysis of pharmaceuticals as a validation method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1598-1603
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• 2004

This paper is an experimental study on the performance characteristic with a variation of capillary diameter and length. The performance characteristic of a refrigeration system is predicted that it is occurring changes of flow pattern and pressure drop in a capillary tube because of reduction of capillary diameter 0.74 to 0.6 mm. The difference between experimental results and analytical results is mainly caused by values of friction factor for using to calculate pressure drop through a small diameter capillary tube under 0.74mm. The experimental equation is derived from capillary tube test data using curve fitting method.